Protractor



y 1935' F. c. HEYERDAHL PROTRACTOR Filed May 16, 1953 ATTORNEY Patented July 30, 1935 UNITED ST TES V rnormAo'roR Frederick C. Heyerdahl; Latrobe, P a. Application May 16, 1933, Serial No. 671,399

8 Claims.

The present invention relates to an improved protractor especially adapted in mechanical drafting and engineering fordeterminingyarious degrees of angles and it is a purpose of the inven- 25 tion to provide a base section for operative position in engagement with andlslidable on-the edge of a T square or ruler, whether or not the T square is horizontal or yer-tical of the drawing board, and a movable section pivoted or ful- 10 crumed on the base section to be disposed in various positions relative to the base section for determining'various degrees and minutes of angles to both the vertical and horizontal and also ,furnishthe reading of angles both to the righ-tand the left in keepingwith the graduations or calibrations .as indicated on adjacent parts of the base and movable sections. l i

It is to be understood that the particulars herein given are in no way limitative, and that while still keeping within the scope of the invention, any desired modification .of details and proportions may be made in the construction of the appliance according to circumstances.

The invention comprises further features and combination of parts to be hereinafter set forth, shown in, the drawing and claimed.

In the drawingz-- v 1 I t Figure 1 isaplan viewof the improved protractor constructed inaccordance with the invention.

Figure 2 is a sectional view online Figurel. Figure 3 is an edge view looking in the direction of the arrow (1 in Figure 1.

Referringto the drawing, I identifies a base section of the protractor, which comprises the base or foundation limb 2, theangularly disposed limbs 3 (which converge) and the arcuate limb .4. The limbs 3 and 4 are beveled as shown at 5 and 6, and the bevel 5 isprovided with two sets of calibrations identified at l and-8. Extending from thecenter of the arcuate limb of the base section is an extension .9,xthrough which a pivot or fulcrum pin Hi passes. One end of the pin has a reduced extension ill (which is square or angular in cross sectional area), fitting in an opening -i2 of a movable section 13 of the protractor. The movablesection of theprotractor is in the form of askeleton segment of substantially triangular-formation, the side limbs 14 of which converge to an apex at iiwhile-the divergent extremities l5 of the-side limbs 14 are connected by an arcuate limb 11. This arcuate limb I! corresponds in curvature withza-nd moves adjacent the arcuate limb 4 of the base section i of the protractor. Said arcuate limbs {and l l are concentric withthe pivot 01' fulcrum pin ID." The movable section l3 of the protractor, since-it is of skeleton construction, includes a plurality-oi brace limbs I8, is and 20, which merge into a .5 central body 21, into the'opening l2 of which the square or rectangular extension H fits.- The end of the rectangular or square extension H is swaged or headed over as shown at 22, in order to :retain the pivot pin 'lll infixed position.

Inorder to retain the extension 9 against the movable section I3 of the protractor a plate 23 overlies the end portion of 'the'extension 9. --In addition to retaining the'extension 9 against the movable section I3 of the;protractor,-.the plate 23 15; furnishes substantial friction for locking the 7 parts, and making less pressure necessary 'between said movable members. The plate 23 has anangular arm 24 riveted at 25 to the limb 20 of the movable section I3 of the protractor. v The 20 pivot pin' in also passesthrough the?plate 23, there being a. washer 26 introduced, and through which thepin HI passes, the washer furnishing more elastic connection and prevent the rotary movable section from turningwhen applying the 25 knurled nut .21, and thus taking up "any unavoidable wear and tear..

Thebase section I of the protractor comprises two parts "and 29, which are welded or otherwise fastened flat togetheras at 30. The part 29 39 has arabbet 3| and engaged therein between it and an adjacent face 30f the part 28 isa rib 32 of the arcuate limb ll of themovable section l3 of the protracton In-other wordssuch constructionprovides a tongue and groove connection 35 between the movableand base sections of the protractor. It is possible to make the base section in a single piece andgroove the .arcuate limb thereof to receive the rib or flange 32, which guides the movable section l3 of the protractor when being manipulated for determining angles. :The' upper face of the arcuate limb l1 ofthe movable section l3 of the protractor is provided with calibrations or ,graduations 33 for cooperation with the calibrations I and-8on the arcuate limb 4 of the base section in determining various angles, the use of. the protractor being clearly obvious, since the movable section l3 thereof may be disposed in various positions even in addition to those disclosed in dot and dash lines in Figure l.

The knurled nut 21 acts to retain the movable section l3 of the protractor any of its different adjusted positions. v a

The double calibrations 33 are employed to givetheangular disposition to the right and left of either edge l4 relative to the foundation limb 2 of the base section and the foundation limb 2 engaging the edge of the leg of a T square whether or not the leg of the T square is in a horizontal or vertical position. The double verniers l and 8 act to give the minutes to horizontal and vertical and also furnish the reading of angles both to the right and left. It will be observed that the zeros on verniers 1 and 8 have an angle of degrees between them, while the angle between the limbs [4 of the movable section is 30 degrees, and the angle between the limbs 3 relative to the foundation limb 2 is 60 degrees. lar line 34 passing through the fulcrum l0 may be applied to the foundation limb 2 of the base section, and it intersects with the foundation limb of the base section exactly one half way between the extreme points of the base section. Furthermore, the calibrations 33 are arranged to occupy one quarter of acircle, 90 degrees, with the pivot pin ID as a hub' center while the zeros of verniers are 60 degrees apart with the pivot pin t0 asa center. s

The Vernier to the right hand reads for the right side of a rotary triangle, the left vernier for the left hand side. The base section of the protractor may slide on a T square or ruler whether it is horizontal or verticaLor may slide adjacent one edge of a triangle when mounted adjacent a T square, therefore it is obvious that every angle in the 21,600 minutes in a circle may be at the command of the user anywhere on the drawing. This device is notonly a protracton but a mu1tisquare protractor, which can be used to transfer lines parallel from one end to another of the drawing.

The protractor will serve a veryuseful purpose in perspective drawings, bridge construction layouts, machinery andship building, line drawings, and in fact everything in the drafting andengineering lines. The triangular movable section may be operated in either direction until one of its converging limbs will register with the apex where a converging limb of the base section and the arcuate limb of the base section come together. In this manner lines of various angles between approximately fifteen or twenty degrees and toward either side may be drawn or constructed by drawing a drafting instrument along either of the converging limbs of the movable section. Furthermore due to the movable section being triangular in formation and the base section having converging limbs, it is possible to adjust the movable' section sothat a converging limb of the movable section may register in alignment with a converging limb of the base section,

that is to say, toward either side, and in this way a drafting instrumentmay be drawn along and against the aligned'registered limbs for drawing a line at a sixty degree angle, while the other converging limb of the triangle movable section may assume a perpendicular position to the base section so that a drafting instrument may be drawn along the edge of the converginglimb disposed perpendicularly, so as todraw perpendicular lines. I

' These features are particularly characteristic A perpendicuw able section, when certain of the converging limbs of both sections register in alignment, causing one of the converging limbs of the movable section to assume an accurate perpendicular position, a movable section pivotally mounted on a member of the base section, the movable section having an arcuate limb concentrically conforming with and slidably engaging the said similarly shaped limb of the base section, the upper faces of the adjacent arcuate limbs having cooperative calibrations, said movable section being of triangular formation in plan view, hence possessing converging limbs, the positioning of either one of which may determine a multiple of different degrees'of angle lines in keeping with the calibrations on the arcuate limbs by operating a drafting instrument along and against either of said converging limbs of the movable section, said arcuate limbs being provided with cooperative tongue and groove connections toguide the movable section in its adjustment.

2. In a protractor as set forth, a base section providedwithan arcuate limb, and having converging limbs which converge in substantially the same direction as the converging limbs of a movable section, when certain of the converging limbs of both sections register in alignment, causing one of the converging limbs of the'movable section to assume an accurate perpendicular position, a movable section pivotally mounted on a member of the base section, the movable section having an arcuate limb concentrically conforming with and slidably engaging the said similarly shaped limb of the base section, the upper faces of the adjacent arcuate limbs having cooperative calibrations, said movable section being of triangular formation in plan view, hence possessing converging limbs, the positioning of which may determine a multiple of different degrees of angle lines in keeping with the calibrations on the arcuate limbs by operating a drafting instrument along and against either of said converging limbs of the movable section, and means for retaining the movable section in any one of its adjusted positions.

3. In a protractor as set forth, a base section provided with an arcuate limb, and having converging limbs which converge in substantially the same direction as the converging limbs of a movable section, when certain of the converging limbs of both sections register in alignment, causing one of the converging limbs of the movable section to assume an accurate perpendicular position, a movable section pivotally mounted on a member of the base section, the movable section having an arcuate limb concentrically conforming with and slidably engaging the said similarly shaped limb of the base section, the upper faces of the adjacent arcuate limbs having cooperative calibrations, said movablesection being of triangular formationin plan view, hence pos- 4. In a protractor as set forth, a base section provided with an arcuate limb, and having converging limbs which converge in substantially the same direction as the converging limbs of a movable section, when certain of the converging limbs of both sections register in alignment, causing one of the converging limbs of the movable section to assume an accurate perpendicular position, a mpvable section pivotally mounted on a member of the base section, the movable section having an arcuate limb concentrically conforming with and slidably engaging the said similarly shaped limb of the base section, the upper faces of the adjacent arcuate limbs having cooperative calibrations, said movable section being of triangular formation in plan view, hence possessing converging limbs, the positioning of which may determine various angles in keeping with the calibrations on the arcuate limbs, means for retaining the movable section in any one of its adjusted positions, the converging limbs of the base section being alignable with a converging limb of the movable section.

5. In a protractor as set forth, a base section provided with an arcuate limb, a movable section pivotally mounted on a member of the base section, the movable section having an arcuate limb concentrically conforming with and slidably engaging the said similarly shaped limb of the base section, the upper faces of the adjacent arcuate limbs having cooperative calibrations, said movable section being of triangular formation in plan view, hence possessing converging limbs, the positioning of which may determine various angles in keeping with the calibrations on the arcuate limbs, means for retaining the movable section in any one of its adjusted positions, said base section provided with converging limbs which converge in substantially the same direction as said converging limbs of the movable section and with either of said converging limbs of the base section a converging limb of the movable section may register, whereby another of said converging limbs of the movable section may be accurately perpendicular to the base section.

6. In a protractor as set forth, a base section provided with an arcuate limb, a movable section pivotally mounted on a member of the base section, the movable section having an arcuate limb concentrically conforming with and slidably engaging said similarly shaped limb of the base section, said base section having converging limbs, the movable section having converging limbs which converge in substantially the same,

direction as the converging limbs of said base section and one of which may register with and in alignment with one of the converging limbs of the base section, with the other converging limb of the movable section out of alignment with the other converging limb of the base section.

7. In a protractor as set forth, a base section, and a movable section, the latter being pivotally mounted upon the former to tilt to the right or left, both sections having converging limbs, whose edges may register in alignment to the right or the left of the longer axis of the movable section when tilted to the right or the left, whereby a drafting instrument may be drawn along either of the registering edges for making lines on an angle between approximately 15 to 20 degrees toward the right or the left.

8. In a protractor as set forth, abase section, and a movable section, the latter being pivotally mounted upon the former to tilt to the right or left, both sections having converging limbs, whose edges may register in alignment to the right or the left of the longer axis of the movable section when tilted to the right or the left, whereby a drafting instrument may be drawn along either of the registering edges for making lines on any angle between approximately 15 to '20 degrees toward the right or the left, both of said sections having interconnected adjacent arcuate limbs, one concentrically conforming with and slidably engaging the other, said arcuate limbs provided with double calibrations cooperative to give the angular disposition to the right and left of either of the converging limbs of the movable section relative to a foundation limb of the base section, thereby giving the angle to both the vertical and horizontal, the pivot for the movable section being located concentric with the arcuate limbs and between them and the apex of the movable section, thereby permitting the calibrations giving angular disposition of the converging limbs.

FREDERICK C. I-IEYERDAHL. 

